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Along with the development of society, technologies, and economics, the profession of washing car is going to be popular gradually.But the environmental protection consciousness and the long-enduring development consciousness of the multitude are not strong enough, thus the wastewater of washing vehicle causes serious pollution. At the same time, the government adopts a series of limiting and emphasis policy, which causes the costs of washing car increasing continuously. In order to wash the car environmentally and economically, washing vehicle with recycling water is indispensable.According to domestic and foreign existing processing technologies of washing car wastewater and its present situations, the coagulation - Sand filtrating - activated charcoal adsorption processing system was proposed.This system takes coagulation theories, sand filtrating mechanisms, and activated charcoal adsorption principles as the foundation, washing vehicle with the recycling water as the goal, establishes the environmental and economical processing model. This topic experiment may be divided into two stages: The still water experiment in laboratory and the flowing water test. The former provides certain parameters to the later.Firstly, through the still water experiment, taking SS （main pollution factor）, pH, and temperature as the monitoring items, determinates the best coagulating drugs and the best using dose, and carries on an economical appraisal to it.Secondly, according to the conditions of flowing water experiments and the influences of coagulation, all factors was analysed separately in this study, including: temperature, assistant coagulating drugs, pH, stirring speed and time（hydropower condition） . The best operating conditions of the coagulation was determinated, under actual revolving conditions. And through the still mock experiment, the manipulating parameters of the Sand filtrating - activated charcoal adsorption craft were determinated, including: filtering velocity and period.Once more, taking still water experiments data as the basic parameters of flowing water experiment, these flowing experiments ware carried on, as following:Qc=250L/h, Qf=250L/h, adds drug 20 L/h;Qc=500L/h, Qf=500L/h, adds drug 20 L/h;Qc=500L/h, Qf=250L/h, adds drug 20 L/h;Qc =250L/h, Qf=250 L/h, adds drug 20 L/h（with 1.5 times dose drug to the best dose）. （The letter c means coagulation, and the letter f means filtrating.）Then the results of the flowing water experiments imply that the second series is the best one. Its final water quality parameters are: SS<5NTU, CODCr <50mg/l, LAS<3mg/l.The average removing rates of the distinct three stages as following:The removing rates of SS, LAS, CODCr of the coagulating stage separately are: 86.28%, 23.12%, and 41.77%;The removing rates of SS, LAS, CODCr of the sand filtrating stage separately are: 9.94%, 3.00%, and 15.48%;The removing rates of SS, LAS, CODCr of the activated charcoal adsorption stage separately are: 2.56%, 13.61%, and 10.72%.The average Final water quality of the distinct three stages as following:
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